This study seeks through the examination of the Aymara, an indigenous people of the Bolivian, Chilean and Peruvian altiplano, to evaluate the effects of environmental factors, primarily oxygen tension, upon pulmonary function, cardiopulmonary relationships and degenerative heart dieases, such as arteriosclerosis, in this unusual population, and to assess the genetic contribution to their anatomical, biochemical and physiological responses to hypoxia. The immediate objectives are (1) to complete the assessment of isozymic variability in this population and to relate that variability to variation in oxygen tension, (2) to initiate biochemical studies of the isozymic variants which are being seen in this population (and are seemingly unique), and (3) to continue the analysis and interpretation of the anthropometric, clinical and physiologic data collected on approximately 2,500 adults and children obtained in the years 1973-1975. Insofar as this latter objective is concerned, emphasis will be upon estimation of (a) the interaction between genetic and non-genetic components of variability in the three altitudinal niches under study, and (b) the effect of migration, particularly the age at which migration occurs, upon the pattern of development normally associated with dwellers in specific niches. BIBLIOGRAPHIC REFERENCES: Barton, S.A., Lenart, V., Palomino, H., Murillo, F., Weidman, W., and Schull, W.J. High Altitude, Indigenous origin, and Continuous Cardiac Monitoring. Aviation, Space, and Environmental Medicine 47(6):592-596, 1976. Schull, William J. and Rothhammer, F. A Multinational Andean Genetic and Health Program: Rationale and Design of a Study of Adaptation to the Hypoxia of Altitude. In: Weiner, J.S. (Ed.) Genetic and Non-Genetic Components of Physiological Variability. London SSHB Pub. 17, pp 139-169, 1977.